Antigen recognition and antibody specificity. Carrier specificity and genetic control of anti-dinitrophenyl-oligolysine antibody

Human thymus-independent antibody response in vitro: III. Precursor frequencies and fine specificity of human B cells stimulated by TNP-Ba in the presence and absence of Con A

Previously, we reported that human B lymphocytes can be stimulated by trinitrophenylated Brucella abortus (TNP-Ba) in vitro to generate T-independent (TI) hapten specific plaque-forming cells (PFC). Furthermore we showed that addition of Con A on Day 3 of culture enhanced the anti-TNP response. In this report the characteristics of the anti-TNP PFC responses elicited by TNP-Ba in the presence or absence of Con A were further defined by estimating precursor frequencies and clone sizes, and by assessing the diversity of the anti-TNP-PFC response using hapten inhibition profiles. Addition of Con A to TNP-Ba-stimulated cultures was associated with a 2.3- to 3.6-fold increase in anti-TNP precursors and was also accompanied by a more vigorous clonal expansion. Fine specificity analysis of anti-TNP PFC revealed that Con A addition resulted in PFC with unique hapten inhibition profiles in that they were less inhibitable by TNP-EACA, TNP-lysine, and DNP-lysine but more inhibitable by DNP-glycine when compared to PFC generated by TNP-Ba alone. These findings suggest that at least some of the additional precursors recruited in the presence of Con A are qualitatively distinct from those activated by TNP-Ba alone since they express different V region gene products.

Specificity and genetic restrictions of the guinea-pig immune response to dinitrophenyl-lysyl-alanyl octapeptides

A series of 2,4-dinitrophenyl (DNP) octapeptides containing L-lysine and L-alanine were prepared to examine the specificity and genetic restrictions of both cellular and humoral immune responses in inbred guinea-pigs. Strains 2 and 13 guinea-pigs were therefore immunized with Lys4-Ala3-Lys(DNP), Lys3Ala4-Lys(DNP), Lys2-Ala5-Lys(DNP) and Lys-Ala6-Lys(DNP). Only Lys4-Ala3-Lys(DNP) was under Ir gene control and could induce both antibody and T-cell responses in strain 2 guinea-pigs. In contrast, Lys4-Ala3-Lys(DNP) injected in strain 13 guinea-pigs and the other DNP-octapeptides injected in strain 2 or 13 guinea-pigs elicited only antibody formation and no specific T-cell mediated response. Antibody formed in the absence of specific T-cell responsiveness in either strain 2 or 13 was hapten specific and lacked the capacity to discriminate the immunizing antigen from closely related DNP-peptides. Antibody produced by animals with specific T-cell responses, on the other hand, was exquisitely specific for the immunizing peptide and could discriminate it from closely related peptides.

Ontogeny of B-lymphocyte function. I. Restricted heterogeneity of the antibody response of B lymphocytes from neonatal and fetal mice

The ontogeny of the ability of B lymphocytes to produce an antihapten response which is heterogeneous with respect to affinity for the antigenic determinant was studied in a cell transfer system. The heterogeneity of affinity of the immune response of lethally irradiated mice reconstituted with syngeneic, adult thymus cells and fetal or neonatal tissues as a source of B lymphocytes was studied. It was found that B cells from 17 day fetal liver or neonatal liver are highly restricted with respect to heterogeneity of affinity as compared with adult spleen or bone marrow. The B-cell population achieves an adult character with respect to heterogeneity of affinity by 2 wk of age. The peripheral lymphoid tissues (spleen) appear to mature in this respect more rapidly than do central lymphoid tissues (bone marrow). Spleens from 10-day old donors behave in an adult, heterogeneous manner while bone marrow from the same donors exhibit a marked restriction in heterogeneity of affinity. Germfree mice produce an immune response which is indistinguishable from conventionally reared adult animals with respect to heterogeneity of affinity. The earlier appearance of the ability to transfer a heterogeneous immune response in spleen as compared with bone marrow suggests that the increasing heterogeneity of the B-lymphocyte population which occurs between birth and 2 wk of age is the result of a differentiation event and not of a somatic mutation or recombination event.

Extent and control of antibody diversity

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Immunologic memory cells of bone marrow origin. Increased burst size of specific immunocyte precursors

Individual immunocompetent precursor cells of (C57BL/10 x C3H)F(1) mouse marrow generate, on transplantation, three to five times more antibody-forming cells localized in recipient spleens during secondary than during primary immune responses. The increased burst size is immunologically specific since antigens of horse and chicken erythrocytes and of Salmonella typhimurium do not cause this effect in marrow cells responsive to sheep red blood cells. Both sensitized and nonsensitized precursors require the helper function of thymus-derived cells and antigen for the final steps of differentiation and maturation. The burst size of primed precursor cells is the same after cooperative interactions with virgin or educated helper cells of thymic origin. The greater potential of these marrow precursors may be attributable to self-replication and migration before differentiation into antibody-forming descendants. In fact, the progeny cells of primed precursor units are distributed among a multiplicity of foci, whereas those of nonimmune precursors are clustered into one focus. The described properties of specifically primed marrow precursors are those underlying immunologic memory. It remains to be established whether memory cells are induced or selected by antigens and whether the thymus plays a role in this process.